1. Field of the Invention
This invention relates to a portable, hydraulically functioning pressing tool for the pressing of coupling elements, with a fork-like receiver and with a clamping pincer which is held in the receiver and which is actuatable by a piston cylinder unit with an integrated restoring spring.
2. Description of Related Art
Portable, hydraulically functioning pressing tools are known and used for pressing coupling elements, such as press sleeves, press fittings, connecting sleeves, tube sections inserted into one another and likewise. The pressing tools have a clamping pincer with clamping jaws which form a pressing space for receiving the coupling elements to be pressed. The pressing force required for the pressing is delivered by a generally hydraulic drive.
Because the apparatus of interest here is preferably used on building sites it is an electrically driven apparatus. By way of example, U.S. Pat. No. 5,040,400 shows a pneumatically functioning apparatus. An electrically driven pressing tool apparatus is taught by European Patent Reference EP-A-0""712""696 (Pamag A G). A conventional apparatus is supplied via electricity mains. However the availability of electrical connection sources on building sites is often very limited. For this reason it is desirable to be able to operate independently of the mains electricity, for example by using a battery. However, as is known, a battery-operated apparatus is very heavily dependent on operating in a manner which is economical with regard to energy, so that a reasonable operational duration per battery charging may be achieved.
With available hydraulically functioning pressing tools, independently ofthe type of the electrical supply, rotation pumps or piston pumps have been applied. All previously known systems have a relatively low delivery power and accordingly the operational duration per stroke of the piston cylinder unit to be actuated is relatively long. Although this is insignificant with an apparatus which depends on mains electricity, with a battery-operated apparatus this operation time is of underlying importance.
U.S. Pat. No. 5,125,324 teaches a mains operated apparatus of the previously mentioned type. The hydraulic pump, which is a piston pump, acts on a piston cylinder unit with an integrated restoring spring, wherein the pump is completely arranged in a hydraulic block between a drive-side gear and a piston cylinder unit.
It is one object of this invention to provide a portable, hydraulically functioning pressing tool having an operational duration per pressing procedure as short as possible, so that the operational duration per charging of the battery with the battery-operated apparatus is sufficient for as many pressing procedures as possible. It is another object of this invention to provide a compact pressing tool which is correspondingly light and which is inexpensive to manufacture.
A portable hydraulically operated pressing tool with the features described in this specification and in the following claims achieves these objects. The apparatus of this invention can use a gear pump. Because a gear pump with a sufficient power requires a relatively large space, the arrangement in the apparatus is of significant importance in order to achieve the mentioned solution without considerably enlarging the apparatus, to avoid additional weight which may be unwieldy. This invention achieves the objects with a modular construction wherein a gear pump is arranged in the hydraulic block and bears in both neighboring modules on both sides of the hydraulic block. This results also in an extremely compact arrangement with correspondingly short hydraulic conduits and accordingly leads to a relatively light pressing tool, even with the incorporated battery.